Plot count hours, each date separately, from non-standard datetime values, in Google Sheets

The data in the 'Input' sheet starts in cell A1 and looks like this:

2021 04 06 7 432021 04 06 11 152021 05 01 10 112021 05 01 13 18

These are datetime values so 2021 05 01 13 18 means 2021 May 1st at 1:18 pm.

How do I plot a line chart that shows the number of occurrences of a particular hour? I need the hours in the X axis, count of hours in the Y axis, and a separate line for each date. Further, the rows should be filtered by the start date in Output!B1 and end date in Output!B2.